HTML Guide for expires

Bad value “Expires” for attribute “http-equiv” on element “meta”.

Expires is not a valid value for the http-equiv attribute in HTML5.

The http-equiv attribute is used with the <meta> tag to configure the HTTP headers of the web page. In HTML5, the allowed values for http-equiv include content-type, default-style, refresh, and security-related headers like Content-Security-Policy. The Expires header is an HTTP header typically set in server configurations or via server-side scripting, not through HTML. To control page caching, consider using server-side headers for Expires or use the cache-control setting if supported by your server.

Here’s how you might correct an HTML document using valid http-equiv values and manage caching through server-side configurations:

Example of Valid HTML <meta> Tags:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Example Page</title>
</head>
<body>
  <h1>Welcome to My Website</h1>
</body>
</html>

Example of Setting Expires at Server Level:

If you’re using Apache, you might set Expires in a .htaccess file:

<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType text/html "access plus 1 week"
</IfModule>

For Nginx, such settings would be in the server’s configuration file:

location ~* \.html$ {
  expires 7d;
}

Using these methods, you ensure compliance with HTML5 standards by handling HTTP headers correctly.